I love to share my extensive gardening knowledge with readers, so that they too can enjoy the wonders of all kinds of verdant plant life.
Catnip (Nepeta cataria) was first discovered in Europe but has since spread to the rest of the world, taken around by intrepid explorers. While it is considered by many to be a weed, and a potentially invasive one at that, others see it as as a cash crop or as an excellent pollinator for them.
A strongly aromatic member of the mint family, catnip has multiple uses: in homeopathic medicine, as a very powerful bee attractant, as insect repellent, and it is also of course globally renowned for being attractive to cats. Sometimes it is referred to as “catmint,” but I prefer the term for this, the most aromatic plant in the whole nepeta group, to be catnip. It’s not the prettiest member of the family, but it is the most potent, having higher quantities of a substance called nepetalactone.
In this article, we'll go over how to plant, grow, and harvest catnip, as well as provide guidance on how to take advantage of its allelopathic, homeopathic, and pollinating qualities.
Tips for Planting Your Catnip
I have a north-facing garden that gets very little winter sun, due to the mountain behind me. Winter conditions have very little relevance to a tough, summer-flowering plant like catnip though. In the winter, it is dormant and can easily survive very cold weather, high winds, frost, and snow.
I planted one catnip plant in full shade. It grew, it flowered. It maybe didn’t get as big as some of those in full sun, but it did OK.
I also planted a couple in a dry border next to a stone wall that got partial sun, and I didn’t water them. They still grew pretty big and flowered.
Those that I grew in full sun did especially well, but they also grew thicker stems, and I’m not sure if that’s a good thing or a bad thing. These thicker stems also had further-spaced-out leaves as well as huge flowers.
Those catnip plants in pots did worst of all, whether in full sun, or sun/shade.
Despite frequent waterings during the hottest weather, I have a feeling that catnip needs to be in the ground, and in a space where its roots can spread far and wide. Shade, semi-shade, dryness, or available waterings don’t seem to be things that worry them too much.
What they do want is space to grow in the ground. Plant them about 18” apart to give them room.
Growing Catnip From Cuttings
Oh this is so easy. If you have a friend or neighbour who has some catnip growing and you have access to a cutting, it roots very easily either in a glass of water or by putting it directly into the ground.
Just pick off a bit of stem that is at least 2” high, remove the lower leaves, and place in water. It will throw out roots in no time, and then you can either pot it on or put in the ground.
We remove the lower leaves to stop it dehydrating too much.
Growing Catnip From Store-Bought Seeds
I’m pretty sure I followed the instructions on my packet of shop-bought catnip seed, and it said to sow them thinly on compost. It then suggested to prick them out when they were big enough to handle into individual pots, then plant them out when all risk of frost was gone.
I did all that, except I started growing them in late summer and planted them out just as winter descended. Most survived, amazingly.
All nepetas are perennial, so they die down in the winter and come up again in the spring. I think some were just too small to survive. That said, we had a surprisingly mild winter that year.
If you try to grow them, what I’ve learned is that catnip has a very good germination rate. From a packet that said it had roughly 200 seeds, I got 200 plants.
Growing New Catnip Plants From Their Seed Heads
To stratify or not, that is the question. In the wild, catnip seeds would be scattered by the wind, find somewhere to settle, and go through a winter before deciding to sprout in the spring.
The web is uncertain whether it needs a cold period or not, but suggests that they should spend at least a day in a freezer before trying to germinate them. The consensus is that unfrozen seeds take longer to germinate.
I will run experiments and update this with my findings.
What to Expect During the Catnip Growing Season
Whether you grew from seed or from a cutting, catnip will start pushing through the soil as soon as at warms up in spring.
You may have planted one stem, but the catnip plant throws up many more. You really want to plant them at least 12” apart. Because once they grow outside in their natural environment, these become very big, bushy plants.
If you had them as houseplants, you’ll realize just how you held them back, because their growth outside will be phenomenal by comparison. By mid-summer, or even earlier if the weather is favourable, they will be in full flower.
They have an extended flowering period going on for at least two months, during which time, they will attract many pollinators into your garden. Bit by bit, the whites of their flowers drop off as seed heads develop, and pollinators continue to show a keen interest.
When kept as a houseplant, Nepeta cataria flowers continually. As soon as you remove a bloom, the plant immediately replaces it. You may find this happens if you live in a warm climate.
Finally comes the day to harvest. Commercial growers choose that narrow time between full seed head development and leaf death. You can harvest their leaves at any time, and some people recommend harvesting the flowers as soon as they appear.
You don’t need to harvest everything though. Leave some stalks and leave some seed heads. Cut what you are taking down to leave at least one stem nodule on the plant. Basically, you can crop almost to the bottom of the stem.
Gather the stems in bunches so they are not packed too tightly together, and hang them upside down in a dark, cool place—or at least a place out of direct sunlight. Leave them there until they are completely dried. Try breaking a stem and see if it breaks cleanly or not. It should snap like a twig. If it doesn’t, leave it there for longer.
Seeds can be collected by tying paper bags over the flowerheads, or else you can cut the blossoms off and place them in something like a muslin laundry bag—where they can be hung up to dry on their own, keeping all their seeds intact.
Preparing Dried Catnip
Nepetalactone, the active ingredient in catnip, is highest in the blooms, then the leaves, and lastly in the stems. Some say there is none in the stems at all, but I’m pretty sure I can smell it there too, in lesser amounts.
How you finish off your dried catnip will depend on what you want to use it for. If it's for catnip tea, or for your cat's pleasure, then you will want to strip the leaves and blooms from the stalks.
If you want to distill the dried catnip for its essential oil, then you really want the stalks too, but you will have to chop them up.
Catnip Essential Oil
Catnip essential oil is a very expensive product to buy, because the yield from catnip is very low. Something like 0.3% of any weight of dried catnip can be extracted.
That said, scientists are very interested in the product, because according to their own research, pure catnip essential oil is more potent than DEET at repelling mosquitoes under laboratory conditions.
Steam distillation is by the far the most common way of extracting catnip essential oil. You will need to have, or have access to, either a glass distillation kit or a pot still like mine.
Catnip in Allelopathy
One of the elements that most attracted me to growing catnip is its propensity for showing allelopathic tendencies. (Yes, I had to Google it too. Keen gardeners aren’t expected to know scientific terms that no-one else uses apart from scientists.)
Allelopathy means the ability of plants to suppress the growth of others. There’s a whole new world out there we didn’t know about, where the roots of one plant communicate with the roots of another.
Basically, catnip plants suppress weeds. They don't do this while they are small and have a small root system. But when they grow and it becomes a power struggle for space, the catnip wins.
I have witnessed this happening around my own garden. I hope farmers take note and plant their pollinator-attracting catnip plants at least a foot away from their crops.
Catnip as a Homeopathic Medicine
In addition to allelopathy, Nepeta cataria has been used for centuries in homeopathy for a number of applications, including:
- as a relaxing agent,
- to settle upset stomachs,
- to induce sweating,
- to induce menstruation,
- to cure diarrhea,
- to increase appetite, and
- to help relieve symptoms of both the common cold and cancer.
Catnip as a Pollinator
All farmers should grow catnip round the peripheries of their fields, because bees of all shapes, sizes, and varieties are strongly attracted to this plant. I have never seen so many bees in my garden since I started growing Nepeta cataria in high numbers.
I almost feel as if I should phone the green save-the-bees people to inform them. The planet needs bees, and we are told they are being killed by insecticides. Yet I think they were all in my garden this summer.
Your crop has to attract the bees, even as a home gardener, and catnip will do that for you. And yet, it repels other insects. How do those two statements marry?
I grew catnip in my kitchen for a year before I planted them in the garden, mainly because my garden is mostly under grass, and I never got round to preparing an area for them.
Those I did manage to plant out in a timely manner have grown fantastically well, but those that stayed home saw me having the most insect-free kitchen ever.
And I slept well at night having breathed their fumes in all day.
The Effect of Catnip on Cats
I have two cats, both siblings. Neither of them react at all to catnip.
While in one sense this has been a great disappointment to me, because I love watching cats react. It is actually good for me as well, because it means I can grow as much catnip as I want, knowing they will not be damaged outdoors or indoors.
I have already learned several of my neighbour’s cats react strongly to it, so I have the beginnings of a business.
Note about pink catnip: Quite a few of my catnip seedlings turned pink when planted in the garden. They greened up over time, but some turned back to red as their seeds started to ripen. If anyone knows why this happens, please drop a comment down below in the comment section
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
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